CVE-2021-43664 – This CVE describes a command injection vulnerab... (How to Fix)

📋 TL;DR

This CVE describes a command injection vulnerability in TOTOLINK EX300_v2 routers that allows attackers to execute arbitrary commands on the device. The vulnerability exists in the 'forceugpo' component and affects users running vulnerable firmware versions. Attackers can potentially gain full control of affected routers.

💻 Affected Systems

Products:

TOTOLINK EX300_v2

Versions: V4.0.3c.140_B20210429 and likely earlier versions

Operating Systems: Embedded Linux firmware

Default Config Vulnerable: ⚠️ Yes

Notes: Affects the specific firmware version mentioned; other TOTOLINK models may be vulnerable but unconfirmed.

📦 What is this software?

Ex300 V2 Firmware by Totolink

View all CVEs affecting Ex300 V2 Firmware →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete device compromise allowing persistent backdoor installation, network traffic interception, lateral movement to connected devices, and use as botnet node.

🟠

Likely Case

Router takeover enabling DNS hijacking, credential theft from network traffic, and denial of service to connected devices.

🟢

If Mitigated

Limited impact if device is behind firewall with restricted WAN access and proper network segmentation.

🌐 Internet-Facing: HIGH - Routers are typically internet-facing devices, making them directly accessible to attackers.

🏢 Internal Only: MEDIUM - Internal attackers could exploit if they gain network access, but requires local network presence.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Public GitHub repository contains exploit details; command injection vulnerabilities are easily weaponized.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Unknown

Vendor Advisory: Not available

Restart Required: Yes

Instructions:

1. Check TOTOLINK website for firmware updates
2. Download latest firmware for EX300_v2
3. Access router admin interface
4. Navigate to firmware update section
5. Upload and apply new firmware
6. Reboot router

🔧 Temporary Workarounds

Disable WAN Management

all

Prevent external access to router management interface

Network Segmentation

all

Isolate router management interface to separate VLAN

🧯 If You Can't Patch

Replace affected device with supported model
Implement strict firewall rules blocking all WAN access to router management ports

🔍 How to Verify

Check if Vulnerable:

Check firmware version in router admin interface under System Status or Firmware Update section

Check Version:

Check via web interface or SSH if enabled: cat /proc/version or show version commands

Verify Fix Applied:

Verify firmware version is newer than V4.0.3c.140_B20210429

📡 Detection & Monitoring

Log Indicators:

Unusual command execution in system logs
Multiple failed login attempts to router interface
Unexpected process creation

Network Indicators:

Unusual outbound connections from router
DNS queries to suspicious domains
Port scanning originating from router

SIEM Query:

source="router_logs" AND ("forceugpo" OR "command injection" OR suspicious shell commands)

📊 Metadata

CVE ID: CVE-2021-43664

CVSS v3 Score: 8.1 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-77

Published: March 30, 2022

Last Updated: November 21, 2024

🔗 References

https://github.com/chibataiki/iot-vuls/blob/main/totolink/command-injection2.md Exploit,Third Party Advisory
https://github.com/chibataiki/iot-vuls/blob/main/totolink/command-injection2.md Exploit,Third Party Advisory

📤 Share & Export

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🔗 Related Vulnerabilities

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